Eucleides in Wikipedia
Eucleides was archon of Athens at the end of 5th century BC.
During the year that Eucleides spent in office (403-402 BC), the murderous oligarchy of the Thirty Tyrants was driven out of Athens and the Athenian democracy re-established. As part of the new regime, Athenians accepted a spelling reform, adopting the Ionian alphabet, which included eta and omega.
There are inscriptions from Athens which used Ionian spelling before it was official and others which continued to use the old Attic spelling after it was repudiated.